In: Anatomy and Physiology
Henry will most likely win the bet. Fainting is possible if one hyperventilates and grunts simultaneously. The mechanism of how this is possible is explained below:
When a person hyperventilates, they take in large amounts of excess and get rid of large amounts of carbon dioxide too quickly. This sudden change in concentration of gases causes vasoconstriction in the blood vessels. Vasoconstriction reduces the blood flow to the brain, which can the person you lose consciousness. To add to this, grunting reduces venous return. Venous return is the blood that returns to the right side of the heart. The blood is pumped from the right side of the heart to the lungs for oxygenation. The amount of blood reaching the lungs for oxygenation falls. If the person is also hyperventilating at the same time, as explained above, vasoconstriction occurs. The combined effect of vasoconstriction and reduced venous return are sufficient to compromise blood blood to the brain and make a person lose consciousness.